I completely agree with what the guys say Rikky. The knocking from the rear is 99% sure to be the front mount for the rear diff - the diff has 3 mounts, 2 at the back of it and 1 at the front. The ones at the back don't wear much, but the one at the front has a much harder life and does (basically) fall to bits over time. As Nodge says, its no biggie in terms of cost or time to replace - but do use a genuine LR/OEM one because an aftermarket one might only last a couple of weeks.
I've been running my Freelander 2WD for a number of years now after catastrophic transmission failure. I find it a great car like this and its been perfectly reliable, but it has hindered where I can take it. Only a couple of weeks ago I got embarrassingly stuck on some wet grass whilst surrounded by 25 "big" landies!!!!!! Admittedly I had just tried to take it 15km up a river bed, where it did go until it got to noisy in the cabin from rocks hitting the car and bits falling off of it! So I think the whole grass thing was the car telling me not to be so stupid in future
It is up to you whether you install the props again - if you do make sure all the tyres are the same make/model and do the 1 wheel up test to make sure the VCU is good, basically...
https://www.landyzone.co.uk/land-rover/tests-new-freelander-owners-should-do-on-their-car.312863/
As said before, if you do need a new VCU it won't cost £1,500! If you need it though, probably best to get new support bearings for it as well - and same buying advice for those as well.... use Genuine/OEM or else you'll be replacing them again in a couple of weeks/months.
If you continue to run without props, I'd also say to let your insurance company know. Your insurance might look good for a quick police check or small claim - but in the event of something serious happening and the insurance company send out an assesor, you need to cover your backside.